1. Field of the Invention
This invention relates to an apparatus for supporting a rotary shaft installed in a vehicle transmission, specifically an apparatus used for freely rotatably supporting the rotary shaft with a casing of the vehicle transmission.
2. Description of the Prior Art
Provided inside a vehicle transmission are a plurality of rotating shafts for transmitting the drive force of an engine, each of which is freely rotatably supported by a roller bearing inside of the transmission casing.
FIGS. 5 and 6 show an example of this kind of apparatus for supporting a rotating shaft 1 in a vehicle transmission.
In order to transmit the drive force of an engine, a gear 2 is fixed to the radially outer peripheral surface of the rotating shaft 1 in an axially middle section of the shaft 1. The gear 2 meshes with a gear that is located on the outer peripheral surface of another rotating shaft that is not shown in the figure. Along with changing the speed between the two rotating shafts, the driving force of the engine is transmitted through the meshing gears.
A cylindrical roller bearing 4 having an outer race 5 is fitted into and fixed to a support section 3a inside of a transmission casing 3. Also an inner track 6 is formed on the radially inner peripheral surface of the outer race 5 in an axially middle section thereof, while an outer track is directly formed on the outer peripheral surface of the rotating shaft 1 (see FIG. 5). Provided between the inner track 6 of the bearing 4 and the outer track or the outer peripheral surface of the shaft 1 are a plurality of rollers 7, which makes it possible for the rotating shaft 1 to freely rotate and be supported inside of the support section 3a. In another example, the rollers 7 are also provided between the aforementioned inner track 6 and an outer track 17 which is located on the radially outer peripheral surface of an inner race 16 fixed to the rotating shaft 1 (see FIG. 6).
In actuality, as shown in FIG. 7, there is a pair of seals 8 which are located on the inner peripheral edges of the outer race 5 which forms the cylindrical roller bearing 4. The outer rim or radially outer peripheral edge of the seal 8 is supported by the side section of the outer ring 5. The seals 8 are of an O-ring shape and the inner rim or radially inner peripheral edge of the seals 8 comes in sliding contact with the outer peripheral surface of the rotating shaft 1 preventing any foreign objects from coming into a section where the rollers 7 are rolling.
As described above, in the conventional apparatus used for supporting the rotary shaft 1 in a vehicle transmission, ordinarily the cylindrical roller bearing 4 is first attached to the support section 3a inside of the casing 3. The rotating shaft 1 is then inserted on the inside of the roller bearing 4 either directly (FIG. 5) or with the inner race 16 supported on the rotating shaft 1 (FIG. 6).
When the rotating shaft 1 is inserted into the cylindrical roller bearing 4 attached on the inside of the support section 3a like this, the gear 2 located on the outer peripheral surface of the rotating shaft 1 in the middle section thereof comes close to the rotating support section 3a and, when inserting the rotating shaft 1 into the cylindrical roller bearing 4, gets in the way, so that the insertion area cannot be seen. As a result of this, it is easy for the rotating shaft 1 to tilt inside the rollers 7, and it becomes hard to line up and support the rotating shaft 1 concentrically with the outer race 5.
In the conventional apparatus for supporting the rotary shaft 1 with the cylindrical roller bearing 4 in the vehicle transmission as mentioned above, the distance L (FIG. 7) between the rollers 7 and the inner rim of the seals 8 is relatively large. Because of this, if the rotating shaft 1 is tilted when it is inserted into the roller bearing 4, either the edge of the rotating shaft 1 or the edge of the inner race 16 often hits the seal 8 on the opposite side (the right hand side of FIGS. 5 and 6) of the bearing 4 from where the shaft 1 is inserted and could damage the seal 8.
The apparatus for supporting the rotating shaft of a vehicle transmission of this invention is intended to solve this problem.